The field of the disclosure relates generally to gas temperature measurement, and more specifically, to methods and a system for measuring gas temperature in harsh environments based on radiation thermometry using thin filaments.
Measuring gas temperatures in a combusting flame or harsh environment downstream of a combustor may include many sources of inaccuracy and non-repeatability. Many of those relate to physical properties of the detector itself. For example, to survive the environment many temperature probes are sheathed in metal tubes, which partially isolates the detector from the environment desired to be measured. Such isolation may reduce a temporal response of the detector. Moreover, a massive protective sheath may also affect a spatial resolution of the detector, e.g., temperature gradients forming through the sheath from the relatively hotter environment toward the relatively cooler environment of the detector. Furthermore, such massive protective sheath may also affect the flow field being measured, e.g., the gas temperature measurements are different between conditions with and without the probe. Such an intrusive configuration may not be acceptable for many practical applications requiring precise and accurate gas temperature measurements.
In addition to the hot gas path of a gas turbine engine, it is difficult to measure temperature profiles accurately in other gas turbine engine areas as well. For example, areas of the compressor gas path experience a reduced temporal response of the detector due to the sheath used to protect the detector, but also because the temperature is lower in those areas of the compressor as compared to areas of the hot gas path. The lower temperature contributes to a reduced response time of the detector. Further, areas of fluid flow other than a gas turbine engine gas path are also difficult to measure accurately using known temperature measurement systems. For example, temperatures in or near a surface flow stream are difficult to measure due to flow streams changing positions for differing flow conditions. Therefore it is desirable to have a temperature measurement system having a detector that can produce temperature profiles or maps in two and three dimensions and be able to self-adjust its position to accommodate variations in a measured flow stream.